Smokers don’t seem to be under any illusions about whether it’s bad for them? When people have conflicting desires, I think what even counts as “self-interest” gets complicated. Often people are acting at cross-purposes to some of their desires.
Reminds me of debating Bentham in high school. If the feeling of self-interest of a murderer acts upon is greater than the self-interest of someone not to be murdered, etc...
Maybe the point is not to reduce judgment to one qualitative idea.
It’s also subjective and dependent on the persons values, beliefs, etc.
The broader point is that self-interest is not purely logical because humans are not purely logical beings.